Mayor de Blasio went back to work Monday after a week gallivanting across the country promoting his “progressive” agenda — and declared it would have been “malpractice” not to take his show on the road.

“You have to walk and chew gum at the same time. I really believe that,” he said during an impromptu visit to the City Hall press room to defend his footloose ways.

“The mayor of New York City is supposed to be a leader in urban America. That’s something that again goes back to La Guardia who helped found the Conference of Mayors and organized mayors around the country to call for the kinds of policies that became the New Deal,” he said, comparing himself to Fiorello La Guardia, the three-term Republican mayor who served from 1934 to 1941.

“The reason you go to Washington, DC, is because that’s where the laws are made, and that’s where the resources are that have a profound effect on this city. To not go there would be malpractice.”

He cited as an example the fight over President Obama’s proposed transportation bill, which could provide billions to the city.

The mayor eased himself back into the work week with staff meetings, a planned dinner with Los Angeles Mayor Eric Garcetti in Queens and two public events.

The first item on the chronically tardy mayor’s public schedule was a 3 p.m. bill-signing ceremony — which started 13 minutes late.

He signed a handful of bills, including one calling for a “comprehensive cultural plan,” a second requiring accurate price listings for used cars, a third mandating an annual report on hepatitis cases and a fourth requiring more advance notice for hotel developments.

The second event on his public schedule took him to Hunter College to deliver remarks at a memorial honoring the late Rep. Herman Badillo, whose wife, Gail, ripped the mayor when he skipped her hubby’s funeral last December.

“What a terrible insult. What a terrible insult,” she had said on WABC radio. “Here the mayor is supposed to represent all the people, and there are a few Hispanics [in leadership roles] in this city — maybe he should take notice.”

Asked during his press-room appearance about spending more time listening to New Yorkers, a defensive de Blasio said he had no plans for town hall-style meetings.

“I don’t have a specific plan, but what I do all the time is go out around different communities and different settings. I go around all over the place — subways, walking down the street — talk to everyday New Yorkers,” he said.

De Blasio returned to New York Saturday after a four-day trip that began in DC, then moved to San Francisco and San Jose, Calif.

While he was gone, the city saw three murders, 13 shootings, a crazed hammer attacker and the funeral of an Amtrak crash victim.